Wheel cylinder bore size question

Brakes for your Classic Mopar

  1. gliderider06

    gliderider06 Well-Known Member

    Messages:
    1,163
    Likes Received:
    189
    Joined:
    Oct 21, 2011
    Location:
    Delaware
    Local Time:
    11:04 AM
    I was going to buy new rear wheel cylinders, for rear brakes, on my 87 Ramcharger. Rockauto has 2 different bore sizes available for my brakes. 7/8 & 1-1/16. What's the difference? Does one give more braking power over the other? Confused on which set to get.
    Thanks Paul
     
  2. OL DODGE

    OL DODGE Well-Known Member

    Messages:
    186
    Likes Received:
    74
    Joined:
    Mar 25, 2012
    Location:
    Fairview Park,Ohio
    Local Time:
    10:04 AM
    Does your Ramcharger have 11 x 2 1/2" brakes ? Most did and that would take a 15/16" bore cylinder Raybestos # WC37235 (same left and right) : You want the correct bore because that will change the braking characteristics a lot . The vehicle was designed to work with a certain area of friction material , a certain wheel cylinder size , certain hardware - it's like having a cam in the engine working with the correct intake,carb, etc,,,,
     
  3. gliderider06

    gliderider06 Well-Known Member

    Messages:
    1,163
    Likes Received:
    189
    Joined:
    Oct 21, 2011
    Location:
    Delaware
    Local Time:
    11:04 AM
    My Ramcharger has 12x3 rear brakes. Rockauto had both wheel cylinders listed for the 12x3 brakes. That's what confused me and i didn't complete the order until I find out.
    Thanks Paul
     
  4. mbaird

    mbaird mbaird FABO Gold Member

    Messages:
    4,239
    Likes Received:
    1428
    Joined:
    Dec 10, 2005
    Location:
    boise, Id
    Local Time:
    9:04 AM
    larger bore = more stopping power and more pedal travel.

    Do you have power brakes ? If so I would go with smaller bore 7/8
     
  5. mbaird

    mbaird mbaird FABO Gold Member

    Messages:
    4,239
    Likes Received:
    1428
    Joined:
    Dec 10, 2005
    Location:
    boise, Id
    Local Time:
    9:04 AM
    Hmmm.... I was selling Dodges in 87 and cannot remember if manual brakes were available.. probably were... I wish I had kept some Data books !
     
  6. gliderider06

    gliderider06 Well-Known Member

    Messages:
    1,163
    Likes Received:
    189
    Joined:
    Oct 21, 2011
    Location:
    Delaware
    Local Time:
    11:04 AM
    I do have power brakes. I'm not sure if they had manual brakes on Ramchargers. I think they were all power brakes.
     
  7. RustyRatRod

    RustyRatRod 30 Degrees Outta Whack FABO Gold Member

    Messages:
    49,145
    Likes Received:
    15335
    Joined:
    Jun 7, 2010
    Location:
    Georgia
    Local Time:
    11:04 AM
    That's a 3/16 difference.
     
  8. mbaird

    mbaird mbaird FABO Gold Member

    Messages:
    4,239
    Likes Received:
    1428
    Joined:
    Dec 10, 2005
    Location:
    boise, Id
    Local Time:
    9:04 AM
    as recent as 87 seems to some of us...lol. You would be surprised at how many things were options then. Those Data books were big ! You could still order almost anything ! We were still ordering slant 6 , 4 sp , rubber mat , vinyl seat base trucks... Radio and heater deletes were still available. Steel wheels with poverty caps were common.
     
    • Like Like x 1
    • gliderider06

      gliderider06 Well-Known Member

      Messages:
      1,163
      Likes Received:
      189
      Joined:
      Oct 21, 2011
      Location:
      Delaware
      Local Time:
      11:04 AM
      Did some more digging... 7/8 Is for 12x2.5 and 1-1/16 Is for 12 x 3"
       
      • Like Like x 1
      • mbaird

        mbaird mbaird FABO Gold Member

        Messages:
        4,239
        Likes Received:
        1428
        Joined:
        Dec 10, 2005
        Location:
        boise, Id
        Local Time:
        9:04 AM
        Interesting that the more powerful one is used with the larger surface area drum...
        might have been a 360 vs /6 or towing package decision.
        I believe there were different GVWs as well for AW150s... but all were 1/2 tons.
         
      • jas0162

        jas0162 Well-Known Member

        Messages:
        302
        Likes Received:
        136
        Joined:
        Apr 23, 2014
        Location:
        kansas
        Local Time:
        10:04 AM
        Does your truck have that big brake on a 9 1/4 half ton rear end? Usually the 12 x 3 brake is on one ton trucks with the Dana 60/70 type rear end. Either way use the bigger wheel cylinder
         
      • roccodart440

        roccodart440 Well-Known Member

        Messages:
        5,046
        Likes Received:
        4033
        Joined:
        Apr 19, 2010
        Local Time:
        11:04 AM
        Just for reference I use 7/8 with manual brakes. Easier to push pedal, more peddle travel. (AKA poor mans power brakes)

        I'd use larger than 7/8
         
      1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
        By continuing to use this site, you are consenting to our use of cookies.